             [:div.auction-end-time
              [auction-end-time-date-picker
               {:selected end-time
-               :on-change #(swap! form-data assoc :auction-offering/end-time %)}]])
+               :on-change #(swap! form-data assoc
+                             :auction-offering/end-time %
+                             :auction-offering/extension-duration
+                               (min extension-duration
+                                    (max-extension-duration-hours @now %)))}]])
           (when (and (or auction? (not editing?))
                      (not editing?))
             [:div.info

      (r/merge-props
        {:type "range"
         :min 0
         :max 24
         :step 0.25}
        props)]
     [:div.input-info

                                 (not (or (not auction?)
                                          valid-min-bid-increase?))
                                 (and auction?
                                      (t/after? (t/plus- @now (t/seconds (hours->seconds extension-duration)))
                                                (from-date (.toDate (js/moment end-time))))))]
        [:div
         [:div.grid.offering-form.submit-footer
          [:div.name
